FIG. 1 is an enlarged side view 100 of a tube coupling disclosed in prior art U.S. Pat. No. 2,850,202 to M. F. Bauer. FIG. 2 is an enlarged and fragmentary cross-sectional view 200 of the forward end portion of the sleeve 13 shown in the prior art device illustrated in FIG. 1. FIG. 3 is a modified form 300 of the forward end portion of the sleeve 13 illustrated in the prior art device illustrated in FIG. 2. FIG. 4 is a fragmentary side view 400 of the wedge insert 20 illustrating the knurled outer surface 23 portion. FIG. 5 is a fragmentary side view 500 taken along the lines 4-4 of FIG. 2 showing principally the knurled section 23.
U.S. Pat. No. 2,850,303 to M. F. Bauer, entitled Double Sealed Compression Fitting, recites, at col. 3, Ins. 54 et seq. with reference to FIG. 1 thereof, “that the invention comprises generally a coupling or connection body 11, a coupling nut 12, and a contractible sleeve 13 adapted to contractibly engage a tube 10. The coupling body 11 is provided at its right-hand end with male threads 14, which are adapted to be threadably engaged by female threads 15 provided in the nut 12 for pressing the sleeve into engagement with the tube. The male threads 14 and the female threads 15 constitute connection means for drawing the connecting body 11 and the coupling nut 12 toward each other. As illustrated, the connection body 11 is provided with a laterally extending outer wall or an entrance end portion 16 with substantially a conical opening 45 extending into said body from said outer wall 16. The conical opening 45 receives the sleeve 13 and the end of the tube 10 and has an internal annular cam surface 17 with a first end portion 46 disposed adjacent the outer wall 16 and a second end portion 47 within the body member disposed longitudinally remote from the outer wall 16. The first end portion 46 has a maximum diameter and the second end portion 47 has a minimum diameter. The internal annular cam surface 17 slopes radially inwardly in substantially a straight line from the first end portion 46 to the second end portion 47 and defines an acute angle with respect to the longitudinal axis of the tube. Extending longitudinally beyond the inwardly converging cam surface 17 is a socket or counter bore 18 which is provided with a terminating end surface 19. The inwardly converging cam surface 17 may be preferably about nine degrees and preferably may lie in a range of approximately eight to twelve degrees, but may be in a wider range of approximately seven to twenty degrees, measured with respect to the longitudinal axis of the tube.
Mounted in the socket 18 is a wedge insert 20 having an abutting end surface 21 and an annular wedge wall or a flare end surface 22. In assembly, the insert 20 is pressed into the socket 18 until the abutting end surface 21 abuts against the terminating end surface 19 for making a sealing engagement therebetween. In order to resist longitudinal movement of the insert 20 out of the socket 18, there is provided a knurled portion 23 which provides longitudinal spaced ribs therearound to-make an interlocking engagement with the wall of the counter bore or socket 18. As the wedge insert 20 is pressed or driven into the counter bore or socket 18, the smooth or unknurled forward portion acts as a guide and elevated ribs of the knurled portion 23 cut or make their own longitudinal grooves into the wall of the socket or counter bore 18 so that the wedge insert becomes a permanent part of the connection body 11. The terminating end surface 19 of the socket 18 is disposed at a reverse slope of approximately five degrees so that when the abutting end surface 21 of the wedge insert is pressed against the terminating end surface 19 a good fluid seal is made therebetween at substantially the bore of the connection body 11. While I preferably use a knurled section to hold the insert 20 in the socket 18, it is understood that any other suitable means may be employed for this purpose.
When my coupling is used for joining steel tubing to a connection body, I preferably construct the wedge insert 20 of steel which is capable of being quench hardenable throughout its entire mass and thereafter tempered or drawn back to a hardness value greater than that of the tube. I find that steel known as 4140, heat treated throughout its entire mass and tempered to a hardness value of approximately 30 to 45 Rockwell, is satisfactory for my insert. When my coupling is used with copper tubing, the insert is preferably constructed of hard brass so that the insert has a hardness value greater than that of the copper tubing. When my coupling is used with stainless steel tubing the wedge insert may be made of hardenable stainless steel. As illustrated, in the drawing, the flare end surface 22 of the insert 20 terminates at its pointed end in a rounded nose 24. It is to be noted that the outwardly converging cam surface 17 and the annular wedge wall or flare end surface 22 define sides of a substantially triangular space comprising a converging annular walled chamber. The annular wedge wall 22 defines in conjunction with the opening 45 an annular converging space 48 pointing away from the outer wall 16 to receive the end of the tube which extends beyond the contractible end portion of the sleeve 13. The annular wedge wall 22 has first end region 49 having a minimum diameter to fit inside the tube and has a second end region 50 with a maximum diameter upon which the end of the tube slides as it is being flared. The annular wedge wall 22 slopes radially outwardly in substantially a straight line from the first end region 49 to the second end region 50 and has an acute angle with respect to the longitudinal axis of the tube. The internal annular cam surface 17 and the and wedge wall 22 are angularly disposed with respect to each other and define an acute angle therebetween. The second end portion 7 of the internal annular cam surface 17 and the second end region 50 of the annular wedge wall 22 converge toward each other, and they have surfaces with a radial distance therebetween less than the wall thickness of the tube to wedgingly receive the end of the tube. The internal annular cam surface 17 has an intermediate portion 51 between the first and second end portions 46 and 47. The intermediate end portion 51 is longitudinally coextensive with and surrounds the first end region 49 of the annular wedge wall 22.
The sleeve 13 has a bore 31 adapted to surround the tube and comprises a continuous annular body 25 provided with rearwardly extending segmental fingers 20 which grip the tube when the nut is tightened. When my coupling is used with steel tubing, this sleeve is preferably constructed of steel which is capable of being quench-hardenable throughout its entire mass and thereafter tempered or drawn back to a hardness value greater than that of the tube. I find that steel known as 4140, heat-treated throughout its entire mass and tempered to a hardness value of approximately 30 to 45 Rockwell, is satisfactory for my sleeve. When my coupling is used with copper tubing, the sleeve is preferably constructed of hard brass so that the insert has a hardness value greater than that of the copper tubing. When my coupling is used with stainless steel tubing the sleeve may be made of hardenable stainless steel.
In the manufacturing of the sleeve, the fingers 26 are provided by making slots 27 in the rearward section thereof at annularly spaced intervals thereabout. In FIG. 1, four slots are used, but any number may be used. The continuous annular body 25 has a leading or forward contractible end portion 28 and a rearward end portion 29. As illustrated, the end portion 29 constitutes the forward terminus for the slots 27. The leading or forward contractible end portion 28 has at its forward end a cam surface 30 which engages the inwardly converging camming surface 17 of the connection body 11. The inside surface of the leading or forward contractible end portion 28 of the sleeve is preferably provided with a major rib 32 which is longitudinally spaced from the end of the sleeve. The inside diameter of the rib 32 is preferably about the same diameter as the bore 31 of the sleeve. In order to provide for making the rib, the inside surface of the forward end portion of the sleeve is recessed at an angle preferably about five degrees, thereby making the recess wall 34. The depth of the major rib 32 may be in the neighborhood of 0.012 inch. The rib 32 is provided with forward edge 35 which constitutes a biting edge for biting into the tube.
The forward edge 35 constitutes laterally extending circumferential walls terminating in circumferential cutting edge to bite and make its own grooves into the outside surface of the tube. The forward edge 35 of the rib 32 faces the annular wedge wall 22. The radial distance between the first end region 49 of the annular wedge wall and the intermediate portion 51 of the internal annular cam surface 17 is less than the lateral wall thickness of the tube plus the lateral thickness of the sleeve between the outer cam surface 30 and the circumferential cutting edge of the rib 32. The outer cam surface 30 prior to assembly has a diameter less than the maximum diameter of the first end portion 46 of the internal annular cam surface 17 and greater than the minimum diameter of the second end portion 47 of the internal annular cam surface 17 and initially contacts the internal annular cam surface 17 between the first end portion 46 and the intermediate portion 51.
The portion of the sleeve in advance of the major rib 32 constitutes an auxiliary body or shell 37. This shell functions to support the outside wall of the tub in advance of the major rib 32. The intermediate part of the entire sleeve, that is, the rearward end of the continuous annular body 25 and the forward end of the segmental fingers 26 is enlarged to provide a tapered or cam shoulder 38 against which a cam shoulder 39 of the nut engages for pressing the contractible sleeve into the inwardly converging cam surface 17 of the connection body 11. The tightening of the nut against the cam shoulder 38 of the sleeve contracts the segmental fingers about the tube for supporting the tube against vibration. It is to be noted that the cam shoulder 39 on the nut oppositely faces the converging cam surface 17 and the terminating end surface 19 of the socket, as well as the flare end surface 22 of the insert.
In assembly, as the sleeve is pressed forward by the tightening of the nut, the outer annular cam surface 30 of the sleeve forceably engages the inwardly converging cam surface 17 of the connection body and thereby produces a camming action which cams or deflects the leading or forward contractible end portion 28 of the sleeve against the tube. The camming action embeds the rib 32 into the tube. The rib 32 makes its own groove in the outer surface of the tube so that as the nut is further tightened, the end of the tube is forced into the triangular space with the inner surface of the tube riding upwardly upon the annular wedge wall or flare end surface 22 of the insert for self-flaring the end of the tube in advance of the major rib 32.
From the above description, it is noted that the coupling during the initial stages of the assembly operates as a no-flare fitting, whereby the outside and inside walls of the sleeve make fluid sealing engagement respectively with the converging cam surface 17 of the connection body and the outside surface of the tube. As the nut is further tightened during the final stages of the assembly of the coupling, the inside surface of the tube rides up upon the annular wedge wall or flare end surface 22 for flaring the tube, whereby another seal is effected between the tube and the insert 20. In other words, during the final stage of assembly, the flare end of the tube is pressed between the sleeve and the annular wedge wall or flare end surface 22 of the insert 20. The force of the end of the tube against the annular wedge wall or flare end surface 22 forces the entire insert into the socket 18, whereby the abutting end surface 21 of the insert makes good fluid seal engagement with the terminating end surface 19 of the connection body.
The circumferential cutting edge of the rib 32 cuts its own grooves into the outside surface of the tube with the laterally extending circumferential wall 35 pressing against the side wall of the groove. The laterally extending circumferential side wall 35 of the rib and the side wall of the groove against which it presses provide a driving engagement between the tube 10 and the sleeve 13 thereby carrying the tube along with the sleeve forcing the inside surface of the end of the tube with a wedging movement against the annular wedge wall 22 to flare the end of the tube in advance of the circumferential cutting edge 35 of the rib 32. The flaring of the end of the tube permits the sleeve 13 and the tube 10 carried there along to move farther into the conical opening 45, for pressing the end of the tube wedgingly into the converging space between the second end portion 47 of the internal annular cam surface 17 and the second end region 50 of the annular wedge wall 22 with the outside surface of the tube making wedging contact against the second end portion 47 of the internal annular cam surface 11 and the inside surface of the tube making a wedging contact with the second end region 50 of the annular wedge wall 22. These wedging contacts limit the movement of the tube into the converging space between the second end portion 47 of the internal annular cam surface 17 and the second end region 50 of the annular wedge. The flaring of the end of the tube also permits the sleeve 13 and the tube 10 carried there along to move farther into the conical opening 45 for pressing the tube and the contractible end portion 28 of the sleeve wedgingly into the converging space between the first end region 49 of the annular wedge wall 22 and the intermediate portion 51 of the internal annular cam surface 17 with the outer surface on the sleeve making a wedging engagement against the intermediate portion 51 of the internal annular cam surface 17 and with the inside surface of the tube making a wedging engagement with the first end region 49 of the annular wedge wall 22. These first and second wedging engagements in combination with the driving engagement between the laterally extending circumferential wall and the side wall of the groove against which it presses arrest the movement of the sleeve 13 into the converging space between the intermediate portion 51 of the internal annular cam surface 17 and the first end region 49 of the annular wedge wall 22. The circumferential cutting edge of the rib 32 upon final assembly of the tube is laterally spaced from the first end region 49 of the annular wedge wall 22 for a distance which is less than the lateral distance of the wall thickness of the tube.
During the final stages of assembly, the shell 37 functions as a preformed chip, filling substantially all the small triangular space between the outside surface of the tube and the inwardly converging cam surface 17, with the result that there is no more space into which loose metal from the tube in advance of the major rib 32 may flow when an extraordinarily heavy force is applied to the tightening of the nut. The wall thickness of the shell 37 may be 0.010 inch to 0.020 inch and the length thereof may be preferably about 1/32 inch or slightly longer. In actual observation, with a coupling cut in section, the small triangular space is substantially undiscernible, because the metal under pressure tends to flow somewhat to make the triangular space in actual construction smaller than it appears upon the drawing, which does not take into account the flow of the metal under pressure. Inasmuch as the annular wedge wall or end surface 22 supports the end of the tube, the coupling may be assembled and disassembled in an unlimited number of times because upon each assembly, the joined parts produce a “rock-bottom,” “hit-home” feeling to the nut, since there is no substantial space into which the metal which is under sealing pressure may flow.
FIG. 2 shows the parts in the assembled condition with the view enlarged. In FIG. 3, Bauer illustrates a modified form of the leading or forward end portion of the sleeve in that the ribs have been replaced by a forward biting edge or shoulder 40 which bites into the tube for making a sealing engagement therewith. The action of the forward biting edge 40 after it makes its own groove into the tube is substantially the same as that for the ribs. The shell 41 is also provided in advance of the forward biting edge 40 in order to support the metal of the tube in advance of the biting edge, as well as to substantially seal the small triangular space between the outside surface of the tube and the inwardly converging cam surface 17 of the connection. The assembly of the coupling with the modified sleeve in FIG. 3 is the same as that for the sleeve shown in FIGS. 1 and 2. From the foregoing description, it is noted that the Bauer coupling claims to be a combination of both the flare and the no flare types of couplings, and thus obtain the advantages of each while overcoming their disadvantages. Bauer claims to avoid the necessity for flaring the tube in advance of assembly of the coupling as would be necessary with a flare fitting. Further, Bauer claims that his invention overcomes the disadvantage of the no flare fitting in that it obtains a “rock-bottom,” “hit-home” feeling when tightening the nut during repeated assembly of the fitting.
In FIGS. 1, 2, and 3 of the drawing, the wall thickness of the tubing is approximately 0.049 inch. With my assembled coupling cut in section and under actual observation, the end of the tube would have a small triangular space 48 in advance thereof. The FIGS. 6 and 7 show the use of my coupling with tubing having a wall thickness of approximately 0.035 inches. Here the triangular space 48 in advance of the end of the tube is somewhat smaller than it is in FIGS. 1, 2, and 3. The FIGS. 8 and 9 show the use of my coupling with tubing having a wall thickness of approximately 0.065 inch. In this instance, the triangular space 48 in advance of the end of the tube is somewhat larger than it is in FIGS. 1, 2, and 3.
My tube coupling accommodates tubing having a wide range of wall thicknesses. One aspect of the invention is that regardless of the wall thickness of the tubing, the distance between the forward end of the tube and the forward end of the sleeve bears about the same relation to each other in the assembled fitting. One would ordinarily conclude that this relationship could not be, and it is difficult to explain the reason therefor. Regardless of the explanation, it is to be pointed out that the rib 32 or the biting edge 40 of the sleeve makes a driving connection between the sleeve and the tube. This driving connection forces the forward end of the tube against the flared wedge wall 22 and thereby self-flares the end of the tube. At the same time, the forward end of the tube is coined or pressed into the triangular space 48. As the forward end of the tube is pressed into the triangular space 48, the outside surface of the forward end of the tube is coined between 47 and 50 and possibly extruding the wedged end of the tube therebetween with the result the end of the tube becomes tapered and elongated. In actual practice, the outer surface of the tube at the forward end thereof at 47 becomes tapered and burnished as the nut is tightened, providing a first perfect sealing area between both sides of the tube against the minimum spaced wall portions 47 and 50.
In the final assembly of the tubing, the minimum spaced wall portions between 47 and 50 arrest the forward movement of the tube therebetween, into the triangular space 48. One novelty of the connection is that the forward end of the tube is arrested in its forward movement between the minimum spaced wall portions 47 and 50, while the sleeve and tube as a unit is arrested in its forward movement between the maximum spaced wall portions 51 and 49, providing a second perfect sealing area. It is to be noted that the invention has a first perfect sealing area for the tube alone between 47 and 50 and a second perfect sealing area for the tube and sleeve as a unit between 51 and 49. These two perfect sealing areas are longitudinally spaced apart and both sealing areas reside between tapered wedging surfaces, namely, the cam wall 17 and the wedge wall 22. Ordinarily when an attempt is made to match machine tolerances to obtain two perfect sealing areas at two longitudinally spaced tapered regions, such as shown in this invention, difficulty arises from the inability to match such tolerances. Both areas do not effect their seal simultaneously. Usually one area “hit-home” or seals before the other. In this invention, the matching of tolerances is accomplished automatically and constitutes one of the unexpected results of my invention. The problem of matching tolerances becomes all the more complex when it is realized that my fitting accommodates tubing having varying tube wall thicknesses. One explanation for the automatic accommodation of matching tolerances arises from two facts: (1) that the coining of the end of the tube at 47 allows the end of tube to wedgingly move forward into triangular space 48, and (2) that probably with tubing of different wall thicknesses, the rib 32 or the biting edge 40 may variably skid or move longitudinally with respect to the tube so that a first perfect seal is made at the end of the tube between 47 and 50 simultaneously with the making of a second perfect seal for the sleeve and tube as a unit between 51 and 49.”
The Bauer patent design is double sealing making: (1) a first perfect seal at the end of the tube between: (a) the second end region 50 of the internal annular cam/wedge wall 22 of the insert 20 and the tube 10, and, (b) the region 47 of the internal cam 17 of the connection body and the tube 10; and, simultaneously (2) making of a second perfect seal for the sleeve 13 and tube 10 as a unit between: (a) intermediate portion 51 of the internal annular cam 17 of the connection body 11 and the sleeve/tube combination, and, (b) the first end region 49 of the annular wedge wall/cam 22 of the insert 20 and the sleeve/tube combination. The Bauer patent discloses a triangular apex 33 meeting at a point and it is this apex into which the sleeve/tube combination is driven. Also disclosed in the Bauer patent is a bore 42 through the insert 20.
The Bauer connection is assembled in a single step with flaring taking place at assembly. The Bauer patent design is vague in describing what tubing materials that it can be used with. Its tubing materials are described as copper, steel, stainless steel. The instant invention is for use primarily with cold worked 300 series stainless steel which is much harder than the tubing the Bauer design uses. The Bauer patent design mentions tubing wall thicknesses of 0.035 to 0.065, the majority of tubing sizes used with the instant invention have a wall thickness greater than 0.065. The Bauer the '303 patent does not mention any surface hardening of the sleeve. It is apparent when viewing FIGS. 1, 2, 3, 6, 7, 8 and 9 of the '303 patent to Bauer is that sleeve 13 is long and includes a long continuous annular body 25 provided with rearwardly extending fingers. It is also apparent from Bauer that sleeve 13 and, in particular, annular body 25 buckles upon loading when nut 12 is torqued as can be seen by the gap between the tube body and the sleeve. Therefore, the “hit home” feeling may not be achieved upon over torquing the nut 12 thus limiting the load that can be applied to the sleeve 13 by the nut 12.
FIG. 6 is a cross-sectional view 600 of prior art U.S. Pat. No. 3,970,336 to O'Sickey for a tube coupling joint. FIG. 6 illustrated herein is substantially the same as FIG. 1 of the '336 patent to O'Sickey. Referring to FIG. 6, bore 611 and bore 612 are illustrated in the joint. Transverse shoulder 613 abuts body 610. Body 610 includes a cam surface 615 which engages radially contractible portion 624 of sleeve 622 as coupling nut 638 is threaded 639 to body 610. Tube 617 includes outer portion 618. Tube 617 may be a relatively thick walled tube and is engaged by radially contractible portion 624 of sleeve 622 which forms a transverse shoulder 620. Enlarged portion 625 includes a tapered shoulder 642 driven by a corresponding surface of coupling nut 638.
U.S. Pat. No. 3,970,336 uses two processes. The first process creates a compression fitting/flared fitting using a hydraulic tool. The compression fitting/flare fitting is then removed and tightened by hand in its connection for final assembly. The O'Sickey '336 patent uses a cylindrically flared tube. The instant invention, among other things, uses a tapered flare. The O'Sickey '336 patent is for use with heavy wall tubing but it does not mention what material the tubing is made of or the pressure it will be used at in service. The O'Sickey patent design does not specify any materials, hardening or surface hardening of any of the components used for flaring, or connection makeup. The O'Sickey patent design seals in two places. One seal point is where the sleeve contacts the tubing and the other seal point is where the sleeve contacts the body. Sleeve 622 in O'Sickey contacts process fluid.
FIG. 6A is a cross-sectional view 600A of a prior art design. FIG. 6B is an enlargement 600B of a portion of FIG. 6A. Autoclave Engineers Fluid Components Division uses a fitting illustrated in FIGS. 6A and 6B for cold-worked stainless steel tubing 655 which includes a sleeve 654 wherein only a mechanical bite 658 is cut into the tubing. Housing 651, die 650, gland 652, and threads 653 between housing and gland are illustrated in FIG. 6A. The design illustrated in FIGS. 6A and 6B includes a sleeve 654 which acts like a cutting tool shaving material from the tubing wall. Annular hook-shaped peel 656 is illustrated in FIGS. 6A and 6B as is the tip portion 657 of the peel. Interengagement 659 of sleeve 654 and tubing 655 as well as the sleeve lip of sleeve extension 660 are illustrated in FIGS. 6A and 6B. Reference numeral 661 illustrates the gap between the sleeve extension 660, tube 655 and annular hook-shaped peel 656. Reference numeral 661 represents the gap between the sleeve extension 660, tube 655 and annular hook-shaped peel 656. No flare is used in the compression fitting of FIGS. 6A and 6B.